A notorious forgery seller from the Operation Bullpen era.
It's possible they offered some authentic items... low cost baseball autographs from common show signers. But they were a major distributor for the forgery ring, so odds are most items with their COA are fakes.
Of course, the only way to know if to show the autograph.
To answer your first, Stan the Man, Inc. is absolutely 100% reputable.
To answer your second question, Stan the Man Sports Memorabilia, Inc. has nothing to do with Stan the Man, Inc. & isn't reputable in any way, shape, or form.